1a.Objectives (from AD-416):
Past and current farming practices in the dryland region of the Pacific Northwest (PNW, northern Idaho, north central Oregon and eastern Washington) have resulted in excessive soil erosion by wind and water, declining soil organic matter levels, poor N use efficiency and losses of biological diversity. These adverse processes are linked to regional degradation of air, water and soil resources and contribute to GHG emissions that drive climate change. This project addresses knowledge gaps associated with the capacity to understand, predict and mitigate PM10/PM2.5 and GHG emissions from dryland agricultural lands.

Objective 2. Scientists are characterizing microbial communities in soil and particulate matter with a diameter of 10 micrometers or less at locations across the western United States to understand dust emissions. These scientists also worked on improving fingerprint methodology by applying micro-organisms to soil as tracers that could provide a powerful tool for understanding dust emission source and fate. Soil containing marked strains of bacteria (tracer organisms) created a unique fingerprint that was identified and traced using microbial analyses.

Objective 3. Analyses of data from field study sampled by ARS scientists at Pullman, Washington, were continued that assess topography, micro-climate, crop rotation and tillage management effects on soil carbon sequestration rates and nitrogen cycling. Long-term cropping system studies were identified to assess soil carbon and nitrogen dynamics including understanding and measuring emissions of greenhouse gasses from agriculture and developing improved technologies and practices to manage these emissions. A static chamber study with automated greenhouse gas flux measurements was field-deployed with different water and nitrogen treatments.

Objective 4. Scientists completed the second year of data from an oilseed cropping system study. Data on soil properties and PM10 (particulate matter with a diameter of 10 micrometers or less) emissions were collected at Lind and Ritzville, Washington, in autumn 2012, where camelina and safflower were grown in rotation with wheat. Information generated from this study will aid in assessing the environmental impact of growing oilseed crops in the Columbia Plateau. Soil was collected and soil quality parameters analyzed from dryland management practices.

Field studies at a farm near St. John, Washington, were conducted by ARS scientists to evaluate wheat plant density and nitrogen fertilizer effects on nitrogen use efficiency. Precision nitrogen management field studies were continued at the Wilke Farm near Davenport, Washington. Preliminary results show that nitrogen use efficiency can be significantly increased by targeting wheat stand density and nitrogen fertilizer rates to specific field locations.

4.Accomplishments
1.
Drought conditions ameliorated by standing crop stubble. No-tillage is less prevalent than conventional-tillage in managing agricultural lands throughout the Unites States and is in part due to a lack of knowledge regarding no-tillage technologies. ARS scientists in Pullman, Washington, discovered that standing crop residues in no-tillage reduces field drifting of snow and results in greater and more uniform storage of soil water as compared to conventionally tilled fields. The greater soil water storage from maintaining standing stubble decreased drought in the following crop and increased potential wheat yield. These findings will promote the adoption of no-tillage for reducing drought levels and soil erosion as well as enhancing crop yields and agricultural sustainability.

2.
Soil carbon sequestration quantified for Pacific Northwest agriculture. ARS scientists at Pullman, Washington, assessed agricultural impacts on soil organic carbon sequestration using published data for different agroclimatic zones of the Pacific Northwest. We discovered that these data were quite variable and devised methodology to express cumulative probabilities of soil carbon change that could be useful for policy makers and marketers to assess the influence of land management changes on soil carbon. These analyses showed that 75% of the converted native ecosystems have lost at least 0.14 to 0.70 Mg carbon per hectare, per year, depending on the agroclimatic zone. Converting from conventional tillage to no-tillage was predicted to increase soil organic carbon from 0.12 to 0.21 Mg carbon per hectare, per year for 75% of situations and was also agroclimatic zone specific. Compared to annual cropping systems, mixed perennial-annual systems would be expected to have soil organic carbon gains of at least 0.55 Mg carbon per hectare, per year for 75% of sites. The variability found among studies suggests that a well validated carbon model for the region would aid evaluation of soil organic carbon changes due to management particularly for specific farms and sites with unique soil organic carbon history and circumstances.

3.
Greenhouse gas emissions assessed for dryland agriculture in Washington. ARS scientists at Pullman, Washington, simulated agricultural impacts on soil organic carbon sequestration and nitrous oxide emissions in eastern Washington using the CropSyst model. Conversion from conventional tillage to no tillage produced the largest relative increase in soil organic carbon storage where increased rates of soil organic carbon storage ranged from 0.29 to 0.53 Mg carbon dioxide equivalent per hectare, per year. The changes in soil organic carbon storage were less with lower annual precipitation, greater amounts of fallow and with changes from conventional tillage to reduced tillage. Simulated nitrous oxide emissions were not very different under conventional, reduced and no tillage. However, nitrous oxide emissions were sufficiently high to offset gains in soil organic carbon from reduced and no tillage, indicating that improved nitrogen management in all systems could contribute to greenhouse gas mitigation. These results will be useful for wheat growers, the Natural Resources Conservation Service (NRCS), Conservation Districts, US Environmetal Protection Agency (USEPA), scientists, and the fertilizer industry, as understanding the effectiveness of agricultural greenhouse gas mitigation strategies is critical for addressing climate change and managing soil sustainability.

4.
Long-term Agroecosystem Research site established at Pullman, Washington. Scientists from Pullman, Washington, were successful in establishing a Long-term Agrocecosystem Research site. This site, located at the Washington State University Cook Agronomy Farm, was one of ten sites selected to be a part of the Long-term Agroecosystem Research network across the United States. Scientists associated with the network have written a document outlining a vision for ARS long-term agroecosystem research. This network will address critical national issues in agricultural sustainability that require long-term research assessments.

5.
Antibiotics do not affect the function of vegetation filter strips. Scientists in Pullman, Washington, and Columbia, Missouri, determined that microbial community structure and function along vegetation filter strips were not affected by the addition of antibiotics to these filter strips. Vegetation filter strips along water ways are critical for maintaining water quality, but the addition of antibiotics to vegetation filter strips is a concern in regions where manure (containing antibiotics) is applied near the filter strips. Our results suggest that field application of manure with antibiotics will not affect the intended function of the filter strips. Therefore, they do not pose harm to humans or to the environment.

6.
Soil crust formation can be predicted from rainfall. Regional assessments of wind erosion are dependent on correctly simulating the formation of soil crusts in response to rainfall in the Columbia Plateau. ARS scientists at Pullman, Washington, found that crust thickness of five major soil types across the Columbia Plateau can be adequately estimated from rainfall. We found that crust thickness exponentially increased with rainfall. This relationship can be used to improve the performance of the USDA-ARS Wind Erosion Prediction System (WEPS) in the Columbia Plateau.